Stocks have paused after getting a fresh leg to their record-setting rally, fueled by improving prospects for a U.S. bill that would slash corporate taxes.

But investors are now waiting to see the final tax legislation, while a potential U.S. government shutdown looms if Congress fails to agree on a spending package.

At the same time, markets have flashed some concerning signals. Copper, which is seen as an indicator of global demand, posted its biggest decline in more than two years on Tuesday, while the U.S. yield curve between two- and 10-year Treasuries has continued to flatten, another potential reflection of worries about the economy.

“There are some inconsistencies in the market right now with what appears to be a very positive economic backdrop,” said Walter Todd, chief investment officer at Greenwood Capital Associates in Greenwood, South Carolina.

The Dow Jones Industrial Average .DJI fell 39.73 points, or 0.16 percent, to 24,140.91, the S&P 500 .SPX lost 0.3 points, or 0.01 percent, to 2,629.27 and the Nasdaq Composite .IXIC added 14.16 points, or 0.21 percent, to 6,776.38.

A top U.S. Senate Republican voiced optimism that congressional negotiators will reach a deal on a sweeping tax overhaul ahead of a Dec. 22 deadline, as senators prepared to vote to authorize talks with the House to bridge differences between their rival bills.

“The initial reaction of the likelihood of a passage is already in the market,” said Randy Frederick, vice president of trading and derivatives for Charles Schwab in Austin. “Now, it’s the details that the market is waiting for.”

German 10-year government bond yields hovered near three-month lows, and U.S. Treasury yields fell across the board as risk appetite slid.

“This market is like a junkie, waiting for the next fix,” said Bruno Braizinha, interest rates strategist at Societe Generale in New York.

“All the good news seems to have been priced in: the U.S. tax reform, the Federal Reserve hike next month and next year. So now the market is waiting for the next positive thing,” he added.

Benchmark 10-year notes US10YT=RR last rose 6/32 in price to yield 2.3349 percent, from 2.356 percent late on Tuesday.

The dollar index .DXY rose 0.2 percent, with the euro EUR= down 0.25 percent to $1.1795.

Sterling touched a one-week low in volatile trading on Wednesday amid growing concerns that a Brexit deal may be unlikely before next week’s key EU summit.

Copper steadied after its sharp falls in the previous session, while other metals fell on concerns that China could see a weaker first half of 2018 and as investors looked to reduce their long exposure before the end of the year.

Copper CMCU3 rose 0.11 percent to $6,550.50 a tonne, after falling more than 4 percent on Tuesday.

U.S. crude slid nearly 3 percent, its biggest daily decline in more than two months, after a sharp rise in U.S. inventories of refined fuel suggested demand may be flagging, while U.S. crude production hit another weekly record.

U.S. crude CLc1 settled down $1.66, or 2.9 percent, to $55.96 a barrel. Brent crude LCOc1 ended down 2.6 percent, or $1.64 a barrel to $61.22.

Spot gold XAU= dropped 0.1 percent to $1,264.37 an ounce.

Additional reporting by Gertrude Chavez-Dreyfuss in New York, Helen Reid in London; Editing by Catherine Evans and Nick Zieminski